5th Wheel Diesel Towing at What RPMs?

[Mopar_Earl]

Originally Posted by rkymntsno

Correct. 2018 Ram 3500 SRW. The Aisin is an option I believe. You look at dealers inventory and a lot of them have the 68RFE transmission. I didn't have any choice other than to keep looking if I didn't want this one. SRWs were scarce at the time I was looking.

Gotcha. My 3500 SRW long bed Aisin was a dealer stock truck. They mostly stocked Aisin 3500 trucks there. Yes the Aisin is an option in the 3500 trucks. Not available in 2500.

I just assumed you had the Aisin due to the 3.42 gearing. That could change a lot. I don't know how the gear ratio spread is between the two. I assume the 68 is a double overdrive? Not sure if the tow/haul mode functions the same between the two. Im not up on the Chrysler transmissions. Always had manual trucks before this Aisin. Definitely love the Aisin. Don't know if I'd of got a automatic if the Aisin wasn't an option.


Earl

[rkymntsno]

Originally Posted by Mopar_Earl

Gotcha. My 3500 SRW long bed Aisin was a dealer stock truck. They mostly stocked Aisin 3500 trucks there. Yes the Aisin is an option in the 3500 trucks. Not available in 2500.

I just assumed you had the Aisin due to the 3.42 gearing. That could change a lot. I don't know how the gear ratio spread is between the two. I assume the 68 is a double overdrive? Not sure if the tow/haul mode functions the same between the two. Im not up on the Chrysler transmissions. Always had manual trucks before this Aisin. Definitely love the Aisin. Don't know if I'd of got a automatic if the Aisin wasn't an option.


Earl

Double overdrive? I have no idea. This is my first diesel and first 5'er. This 3500 is a beast. So happy with it. As long as it treats me right, I'll stick with it.

[garyp4951]

The 68 is a great transmission, but it is not rated medium duty like Aisin.
The 3.42 gearing is the only choice in either trans, unless you go dually, but might have changed for 2019.

[AKRUEBBE]

Originally Posted by rkymntsno

We're new to towing something this big and heavy and was wondering, at what rpm do you tow at and what gear? The 5th wheel was right at 13,500 lbs. Our TV as you can see below is the CTD 6.7, 6 speed, 3.42 rear axle. At 65 mph, 6th gear, we're at about 1800 rpms. It would downshift to 5 occasionally, but not unnecessarily. It felt like it was "lugging" in 6th, and getting around 10 mpg. I downshifted to 5th gear and left it there the remainder of the trip. It stayed around 2,000 rpms and seemed to like that better. Gas mileage on the "lie-o-meter" continued to say around 10 mpg in 5th, same as 6th gear. All the numbers on the truck remained just about the same, oil pressure, trans temp, oil temp, etc. So am I right in towing around 2000 rpms in 5th gear?

I have a 2017 RAM 3500, diesel, Aisin 4.10 and at 60 to 62 mph, I'm right around 1,750 rpms. It never struggles. My first 3500 had the 3.42 axle ratio and it doesn't compare to the 4.10 for acceleration and pulling power.

[rkymntsno]

Originally Posted by AKRUEBBE

I have a 2017 RAM 3500, diesel, Aisin 4.10 and at 60 to 62 mph, I'm right around 1,750 rpms. It never struggles. My first 3500 had the 3.42 axle ratio and it doesn't compare to the 4.10 for acceleration and pulling power.

I'm not here to defend either transmission. Lugging might have not been the right word. It would just downshift to 5th gear at times like it's supposed to. They weren't mountains we were going through but they were hills.

[AKRUEBBE]

Originally Posted by rkymntsno

I'm not here to defend either transmission. Lugging might have not been the right word. It would just downshift to 5th gear at times like it's supposed to. They weren't mountains we were going through but they were hills.

I use cruise control all the time on freeways. It will downshift anytime the speed I have it set at drops by 2 mph. Doesn't bother me. There isn't a mountain pass that I've encountered where I couldn't hold a steady 60 mph without reaching the rpm danger zone.

[Mopar_Earl]

Originally Posted by rkymntsno

I'm not here to defend either transmission. Lugging might have not been the right word. It would just downshift to 5th gear at times like it's supposed to. They weren't mountains we were going through but they were hills.

That's normal as the 68 is probably a double overdrive trans. So 5th and 6th would be overdrives. The only time you have to worry is if it's hunting gears. Meaning it shifting between two gears a lot. In that case to preserve your clutches, lock out the one gear until the situation is over.
Even on a flat with a load like your trailer, it will downshift for the slightest grade or if you push more throttle to her. Don't be surprised if it drops to 4th direct gear.


Earl

[rkymntsno]

Originally Posted by AKRUEBBE

I use cruise control all the time on freeways. It will downshift anytime the speed I have it set at drops by 2 mph. Doesn't bother me. There isn't a mountain pass that I've encountered where I couldn't hold a steady 60 mph without reaching the rpm danger zone.

Yea it's easier just to keep it on cruise control. I don't think it dropped to 4th at all the entire trip, going or coming. I'm new to this stuff and that's why I really like this forum. A lot of experience here, from everyone. I actually think it was the Cummins forum I saw where they were discussing dropping to 5th and leaving it there and it was better for them.

[PlayersZ28]

Originally Posted by norty1

I tow a 38.5' fiver. I just put it in tow haul and let the engine/transmission do what it's designed for.

When I am cruising under 60 and on a flat surface, I will disengage tow haul and let it up-shift. I just have to remember to put in t/h for braking.

I avg 11 mpg towing.

Same here. T/H mode will be ~1600rpm in 6th @ 65mph, ~1600rpm in 5th @ 55mph. With no head/side winds I can hold 6th @ 60mph, any wind load and it'll downshift. If I'm running flat roads then I'll turn off T/H and run with cruise. I always turn on the exh brk as soon as I startup. Would be nice if T/H mode auto turned on the exh brk. My TC will lock real early (I run an Insight so I see EGT, gear, TC lock, etc)

[AKRUEBBE]

Originally Posted by norty1

I tow a 38.5' fiver. I just put it in tow haul and let the engine/transmission do what it's designed for.

When I am cruising under 60 and on a flat surface, I will disengage tow haul and let it up-shift. I just have to remember to put in t/h for braking.

I avg 11 mpg towing.

So you are indicating that in Tow/Haul mode it prevents the transmission from shifting into 6th gear? Everything that I read on the Tow/Haul feature is that it keeps the transmission in each gear longer, which makes sense. Nothing I've read speaks to keeping it out of 6th gear.

[Mopar_Earl]

Originally Posted by AKRUEBBE

So you are indicating that in Tow/Haul mode it prevents the transmission from shifting into 6th gear? Everything that I read on the Tow/Haul feature is that it keeps the transmission in each gear longer, which makes sense. Nothing I've read speaks to keeping it out of 6th gear.

Old school tow/haul would lock out overdrive. Not anymore. Especially when you have double overdrives. You're correct, on late model Ram's it changes shift points and causes progressive downshifting. I run in tow/haul all the time cause I prefer the shift points it offers. Also it makes the exhaust brake a lot more aggressive. On Rams you can lock out gears down to 1st. But you have to manually do it.


Earl

[rkymntsno]

Originally Posted by Mopar_Earl

Old school tow/haul would lock out overdrive. Not anymore. Especially when you have double overdrives. You're correct, on late model Ram's it changes shift points and causes progressive downshifting. I run in tow/haul all the time cause I prefer the shift points it offers. Also it makes the exhaust brake a lot more aggressive. On Rams you can lock out gears down to 1st. But you have to manually do it.


Earl

Exactly. That's what I did, I locked out 6th gear cuz we were running hills. Just kept it from downshifting on the hills cuz in 6th at 65 we're at about 1700 rpms.

[MontyRV]

Originally Posted by Mopar_Earl

Your 3500 truck with 3.42 gears has the Chrysler trans, not the Aisin? Did a quick look. The 3.42 was an option on the 68 trans. First I've heard of it. Only seen 3.73. Aisin you only have the 3.42, no other option unless you go dually with Max tow group.

So you have the lesser rated engine with the 68 trans. Does that change your gvwr and gcwr compared to the Aisin?


Earl

Having the 68RFE instead of the Aisin drastically reduces your capability numbers. Problem is, most guys just look at generic numbers for their truck, and think they're ok. Most of the time, they're not. Ram has bodybuilder sheets that show every number with all truck options. Most people don't have a clue.

[MontyRV]

His truck, if it's 2wd, has a payload of 5,790LBS
MAX TOWING 20,620LBS


If 4wd,
Payload 4,120LBS
MAX TOWING 16,650LBS


That's from the Ram website.

[Mopar_Earl]

Originally Posted by MontyRV

Having the 68RFE instead of the Aisin drastically reduces your capability numbers. Problem is, most guys just look at generic numbers for their truck, and think they're ok. Most of the time, they're not. Ram has bodybuilder sheets that show every number with all truck options. Most people don't have a clue.

Yep. Also pays to look at the door sticker when you're looking at the truck at the very least. I've used the bodybuilder several times for various reasons. Lots of very detailed info provided. When I bought my 07 2500 I wanted regular cab to get the highest payload I could. Needed a 4 door truck so went to a 18 3500 SRW long bed to get the highest payload. Also went tradesman for less options for less weight. I'm no where near dually weights. Maybe 10 years down the road.


Earl

[rkymntsno]

My 2018 Ram 3500 CC Longbed SRW 4x4 has a payload of 4200. That is backed up by my weights at the CAT scales. Of course two fuel tanks filled at 92 gallons, along with the auxiliary tank itself, and a hard tonneau cover over a long bed. took up some of that payload. Trust me. I know my numbers. I got burned with the Ram 1500 and just skipped over the 2500 altogether. A lot of 2500 owners are over their payload pulling a fifth wheel. So many deny it until they go to the CAT scales and find out.

[hboy]

Originally Posted by rkymntsno

So am I right in towing around 2000 rpms in 5th gear?

I tow at about 16-17,000 loaded and lock out of 6th gear as well. I like 65mph towing and I'm around 2,000 RPM's too. I'd like to go to 6th gear on flat land have have done it in the past. I did read (online of course) that towing heavy in 6th gear with the 68rfe is not good. I don't know why but I did believe that.

I haven't towed heavy in 6th gear much, but did just let Chrysler replace my 68RFE. I don't know if it could be related at all, but I was having a high pitch whine in 6th gear when driving. Most noticeable at highway speed when taking my foot off the accelerator. She would whine in 6th gear as I was coasting. Dealer said the planetary gear(s) had failed with some metal shavings in the tranny.

So for me, after that i'm gonna keep it locked out of 6th. Again, I don't know if towing heavy in 6th had anything to do with the failure, but locking out of 6th doesn't seem like a bad idea. When I tow lighter (5K lb boat) i'll use 6th.

[rkymntsno]

Originally Posted by hboy

I tow at about 16-17,000 loaded and lock out of 6th gear as well. I like 65mph towing and I'm around 2,000 RPM's too. I'd like to go to 6th gear on flat land have have done it in the past. I did read (online of course) that towing heavy in 6th gear with the 68rfe is not good. I don't know why but I did believe that.

I haven't towed heavy in 6th gear much, but did just let Chrysler replace my 68RFE. I don't know if it could be related at all, but I was having a high pitch whine in 6th gear when driving. Most noticeable at highway speed when taking my foot off the accelerator. She would whine in 6th gear as I was coasting. Dealer said the planetary gear(s) had failed with some metal shavings in the tranny.

So for me, after that i'm gonna keep it locked out of 6th. Again, I don't know if towing heavy in 6th had anything to do with the failure, but locking out of 6th doesn't seem like a bad idea. When I tow lighter (5K lb boat) i'll use 6th.

Same here. The only thing I pull is my 5'er, and that's a heavy pull. But if I've got straight flat land, I'll keep it in 6th. But if hills are coming up and I know it's gonna shift anyway, I'll lock out 6th and keep it in 5th.

[garyp4951]

Originally Posted by MontyRV

Having the 68RFE instead of the Aisin drastically reduces your capability numbers. Problem is, most guys just look at generic numbers for their truck, and think they're ok. Most of the time, they're not. Ram has bodybuilder sheets that show every number with all truck options. Most people don't have a clue.

That would be only in a dually, in which the Aisin gives you around 30k max trailer,verses 22k with the 68 trans.

[AKRUEBBE]

Originally Posted by garyp4951

That would be only in a dually, in which the Aisin gives you around 30k max trailer,verses 22k with the 68 trans.

x2 love the Aisin!!